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Global patterns of kelp forest change over the past half-century


Krumhansl, KA and Okamoto, DK and Rassweiler, A and Novak, M and Bolton, JJ and Cavanaugh, KC and Connell, SD and Johnson, CR and Konar, B and Ling, SD and Micheli, F and Norderhaug, KM and Perez-Matus, A and Sousa-Pinto, I and Reed, DC and Salomon, AK and Shears, NT and Wernberg, T and Anderson, RJ and Barrett, NS and Buschmann, AH and Carr, MH and Caselle, JE and Derrien-Courtel, S and Edgar, GJ and Edwards, M and Estes, JA and Goodwin, C and Kenner, MC and Kushner, DJ and Moy, FE and Nunn, J and Steneck, RS and Vasquez, J and Watson, J and Witman, JD and Byrnes, JEK, Global patterns of kelp forest change over the past half-century, National Academy of Sciences of The United States of America. Proceedings, 113, (48) pp. 13785-13790. ISSN 0027-8424 (2016) [Refereed Article]

Copyright Statement

Copyright 2016 the Author(s)

DOI: doi:10.1073/pnas.1606102113


Kelp forests (Order Laminariales) form key biogenic habitats in coastal regions of temperate and Arctic seas worldwide, providing ecosystem services valued in the range of billions of dollars annually. Although local evidence suggests that kelp forests are increasingly threatened by a variety of stressors, no comprehensive global analysis of change in kelp abundances currently exists. Here, we build and analyze a global database of kelp time series spanning the past half-century to assess regional and global trends in kelp abundances. We detected a high degree of geographic variation in trends, with regional variability in the direction and magnitude of change far exceeding a small global average decline (instantaneous rate of change = −0.018 y−1). Our analysis identified declines in 38% of ecoregions for which there are data (−0.015 to −0.18 y−1), increases in 27% of ecoregions (0.015 to 0.11 y−1), and no detectable change in 35% of ecoregions. These spatially variable trajectories reflected regional differences in the drivers of change, uncertainty in some regions owing to poor spatial and temporal data coverage, and the dynamic nature of kelp populations. We conclude that although global drivers could be affecting kelp forests at multiple scales, local stressors and regional variation in the effects of these drivers dominate kelp dynamics, in contrast to many other marine and terrestrial foundation species.

Item Details

Item Type:Refereed Article
Keywords:kelp forests, ecological, coastal ecosystems, climate change, global change, Laminariales
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Ecological physiology
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Adaptation to climate change
Objective Field:Ecosystem adaptation to climate change
UTAS Author:Johnson, CR (Professor Craig Johnson)
UTAS Author:Ling, SD (Dr Scott Ling)
UTAS Author:Barrett, NS (Associate Professor Neville Barrett)
UTAS Author:Edgar, GJ (Professor Graham Edgar)
ID Code:112657
Year Published:2016
Web of Science® Times Cited:356
Deposited By:Ecology and Biodiversity
Deposited On:2016-11-22
Last Modified:2018-04-18

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